No Piston movement

westcoastchi · Posted: December 9, 2006, 10:20 pm Post subject: No Piston movement

I've got a bobber project bike.

I honed the cylinders and put new rings and new timing chain tensioner in an 81 motor. It has a blocked off electric start with a block off kit.

Put the motor back in the bike and did a compression check with 110Right cylinder, 115psi Left cylinder. Great I'm thinking, put the carbs, pipes, etc. back on and kick it over for a test start and...nothing. Feels like there is no compression. I do another compression check and 0, nada, nothing. The only difference between the first compression check with the 110/115 and now is I put the pipes and carbs on it.

I put the bike up on its center stand pop it in 3rd gear and rotate the rear tire to see I had any piston movement/compression and ... 0, nada, nothing.

Any suggestions on what the heck is going on here?

xsjohn · Posted: December 9, 2006, 10:44 pm Post subject: Re: No Piston movement

My buddy always said his kick starter didn't work. One day I watched him grab the clutch and try to kick it. No Go. I guessing something in the clutch. Did you also put the left side cover on with the carbs and pipes and maybe something held the clutch open?. If not no idea.

John

xsjohn · Posted: December 10, 2006, 1:49 am Post subject: Re: No Piston movement

My buddy always said his kick starter didn't work. One day I watched him grab the clutch and try to kick it. No Go. I guessing something in the clutch. Did you also put the left side cover on with the carbs and pipes and maybe something held the clutch open?. If not no idea.

John Double post sorry

kingwj · Posted: December 10, 2006, 8:35 am Post subject: Re: No Piston movement

Put it in gear and see if the kick start turns the wheel. That will verify there is a continuous path from the engine to the rear wheel. You might want the bike on the ground to take stiction out of the equation. I agree with xsjohn, the left side cover would be the first thing I'd take off.

westcoastchi · Posted: December 18, 2006, 10:20 pm Post subject: Re: No Piston movement

I pulled the right side cover off and then pulled off the right side cover of my parts bike to do a side by side comparison. They looked the same. I pulled the kick starter off the bike and re-installed it with no change. There is definetly some friction that I'm kicking against but it isn't moving the pistons or the valves.

I kicked the parts bike over and that kick starter was engaging and turning the motor over. So I pulled the kick starter off the parts bike and installed it into the bike I've been working on with the same result, not turning the motor over.

I heard that sometimes the slot on the motor case where the friction clip rides back and forth in will get worn preventing the kick start gear from engaging all the way into the ring gear. The work around was to place the friction clip just to the right of the slot on the motor case that it was to slide back and forth on. This produced the same results and made me have to jockey the kickstart lever around until the kick start gear meshes into the ring gear.

Any suggestions?

grizld1 · Posted: December 18, 2006, 11:16 pm Post subject: Re: No Piston movement

I think what the guys are trying to tell you is that the kick starter hooks up to the tranny input shaft, so if the clutch is slipping the kickstarter won't turn the motor over. Check clutch adjustment.

westcoastchi · Posted: December 20, 2006, 1:54 pm Post subject: Re: No Piston movement

I adjusted the clutch, it was out of adjustment and it helped a little but still took me standing on the kick starter and jumping up and down to get it to move.

Then I went with, what did you do last and work from there. So I pulled off the left engine cover and tried to kick over, no change it barely moved. Then I pulled off the stator, hey it kicks over just fine.

Thats when the 4 brain cells I have left kicked in. I remember when I put the stator on it had this piece that looked a little melted. I think its the pickup unit that has the magnent in it. I think it was binding against the rotor keeping it ... and the motor from turning.

The pickup unit is riveted into the stator, can I get just that part or do I need an entire new stator?

xsjohn · Posted: December 20, 2006, 2:21 pm Post subject: Re: No Piston movement

There is some clearance between rotor and pickup coil. Can't imagine how the crank moved to the left unless the nut on the drive side of the crank (right side) has come loose. That nut (on the clutch side) holds the crank in place. Did you check to see if the rotor was tight. Never heard of the crank coming loose from the center splines but anything is possible.

The magnet is built into the rotor on the outside of the brass rings.. The pickup coil (no magnet) has windings that create a current when the magnet on the rotor passes by. Better check it out good cause what you described can cause a multiple of problems. Charging, ignition and damage to the stator and rotor and brushes and the brush holder..And pocket book......Is there damage to the inside of the stator or the outside of the rotor.....?

I have replaced the pickup coil before without replacing the stator and visa versa. Finding one is another story. Might test the pickup coil you have using a ohm meter. Maybe it is still good somehow. On its plug (the other end) there are three blades. If memory serves me the sideways one is ground the other two are the two coils in the pickup. Between ground and either blade shoud read 600-700 ohms. Both sides need to work. Again if my memory serves me. Wow.......

If you have the type where the pickup coil is riveted on you will need to grind off the tip of the rivits and grab the end and turn it out with visegrips. Then replace them with screws. There should be threads for a screw in the stator housing after you get the revits turned out.

This is a weird situation that I havn't heard of and would not like to have happen. Let us know what you find. Wow.......

Loose rotor....?......Stator mounted wrong.......?
Loose nut on right side of crank........?

On my spare engine the crank proprudes out from the case 2.523 inches with everything off of the crank (left side).

John? WOW

westcoastchi · Posted: December 23, 2006, 12:01 am Post subject: Re: No Piston movement

Found the pick up coil on the inside of the stator was ...melted. Looking at it from the outside it looked fine but when you flipped it over and looked inside the stator you could see the pickup coil was melted. This caused the stator to sit c***-eyed and bind against the rotor keeping the motor from turning over when I was kicking it over.

Went down to the local bone yard here in San Diego and they sold me a pickup coil for $50. I took a hack saw blade and sawed a groove in the rivets, effectively making them into a standard headed screw. I then backed out the rivets with a flat bladed screw driver, pulled out the old melted pickup, cut the wires and soldered in the new pickup coil, and used the rivets (that I turned into standard screws with the hacksaw blade) and screwed the new used coil into the stator.

Stator fit nice and snug over the rotor, no binding, and the motor turns when I kick it over.

Now I'm on to the next issue, with the plugs pulled and attached to the spark plug caps I laid the plugs against the side of the engine so they are grounded and turn over the motor. I should see the plugs spark up, right? because they aren't. The key is on and I've got a battery in it.

xsjohn · Posted: December 23, 2006, 12:18 am Post subject: Re: No Piston movement

Did this thing run before the top end rebuild.
John

ttmaniac · Full Member Joined: Dec 22, 2006 Posts: 468

I blew my buddys camchain (a first) the other day....instantly the bike had no compression....i was lucky nothing was damaged internally (i think)...just thought I'd share it with you all....HOT TIP:don't use a old camchain in a high compression motor...lol

westcoastchi · Posted: December 23, 2006, 6:07 pm Post subject: Re: No Piston movement

The 81 motor is from a motorcycle boneyard. Not sure if it ran before but I needed to replace the timing chain tensioner and while I had the heads off put new stock size rings on and honed the cylinders. Compression now checks in at 105 and 110 psi.

Frame was a titled frame and a parts bike is supplying the rest of the parts.

xsjohn · Posted: December 24, 2006, 1:19 am Post subject: Re: No Piston movement

Was the magnet on the outside of the rotor face damaged when the pickup coil welded itself. If not. Ohm meter frenzy time. Wiring diagram and shop manual helps a lot. This is where I start swaping parts if I get stuck with the meter. May have to clean all the wire plugs and check all grounds and all of the ignition components with the meter until you can find the problem. Switches too. The less parts you have to swap out with the smarter you have to get. TCI ignition module? There is lots of posts on this TCI subject. Sorry I couldn't be more help.

John

westcoastchi · Posted: February 20, 2007, 11:37 pm Post subject: Re: No Piston movement

I went to the discussion on Transistor Controlled Ignition and gave swapping out the transistor with a radio shack transistor and it worked fine. Nice bright spark on the plugs now.

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